$17/mo – Finance TerraBloom ECMF-150, Quiet 6″ Inline Duct Fan with Variable Speed Controller – Ventilation Exhaust Fan for Heating Cooling Booster and Grow Tents | Buy Now, Pay Later

Size: 6″ (288CFM, 36W, Regular Case)

re are no brushes to wear out and the ball bearings are rated at 70,000 hours, 8 years, continuous. The kicker is the control circuit. You can use the supplied potentiometer for manual control, but there is a 300mA, 10V supply for the pot that can also be used for signal conditioning from logic level control circuitry. These will take a DAC voltage, a digital potentiometer wiper, or a PWM signal. It just needs to fit in that 0-10V window. The PWM signal is very tolerant of PWM frequency. You just want to make sure the square wave bangs the full 0-10V input range to be able to access the full RPM range of the fan. The only down side I can find is that there is a soft start characteristic where there is a time constant to speed changes. For my application the time constant is a bit long but in practice shouldn’t be too noticeable. The time constant makes for about a 10 second spin up from stopped to full speed. Most won’t care but there is a bit of lag that may be an issue for some applications. Construction is sturdy and these seem very well designed and built. The outer case is steel and nicely formed and painted, but what mattered more for me are the innards. The inlet is sculpted to smooth air flow to the rotor, and the air channel expands back out to full ID to slow the air into the stator area. 7 rotor blades and 7 stator blades. Mold lines are clean and there is minimal flash. They really seem well-built. And maintainable. You will void your warranty but it looks like these can be disassembled if they ever do need lubrication or cleaning. I say looks like because I haven’t actually tried it but phillips screws are used throughout. There is a tamper seal that will tell the tale, though. And they are quiet. Way more quiet than bilge fans. At low speeds you can’t even hear them. At high speed you get some wind noise and some inlet whine (5000 RPM at full speed) but it’s a huge improvement over the bilge fans. When they say quiet, it’s not exaggerating. 5 stars hands down. These ECM fans are near perfect for any automated fan control applications. It just takes level shifting of some sort to control these with PCs, Arduinos, or Raspberry Pi SBCs. I2C and SPI DACs and pots that are high voltage tolerant on their outputs should work fine. There is also an open collector tach signal for those who want closed loop control or just to know the fans are turning. PWM control is new to these fans so if that’s important to you, just look for the 4-conductor 1/8” miniplug connectors. The new ones use those. Customer service is great and Steve has been super helpful in getting answers to my inane questions. I don’t have much time with these to comment on longevity but with the alternative control built in, EC motors, and ball bearings on top of surprising engineering in the inlet, rotor, and stator regions, this series of fans are hands down winners.

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I’ve been using bilge fans to provide simulated wind for a flight simulator but they are sleeve bearing, brushed, DC motors and wear out under sustained high RPM operation. I started looking for an alternative and found these. Early into their use but they are perfect! With electronic commutation the